Electrophoretic Motion of a Spherical Particle with a Thick Double Layer in Bounded Flows

Shugai, A. A.; Carnie, Steven L.

doi:10.1006/jcis.1999.6143

Cited by 100 publications

(158 citation statements)

References 24 publications

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“…Its applicability and the accuracy for the electrophoresis problem of the present type were examined previously by Hsu and Kao [22] applying it to solving the electrophoresis of a sphere along the axis of a cylindrical pore, and comparing the results obtained with those of Ennis and Anderson [9] and Shugai and Carnie [10]. The former is based on a reflection method, which is unreliable if the ratio (particle radius/pore radius) is large, and the latter uses a numerical approach, which is inaccurate if this ratio is small.…”

Section: Resultsmentioning

confidence: 95%

“…In fact, when a boundary is present the electrophoretic behavior of entities is influenced by several key factors such as the increase in the viscous drag, increasing induced charge both on the approaching surfaces of the entity and boundary, the enhancement of the local electric field on particle surface, and the effect of possible EOF. Previous efforts regarding the boundary effect on electrophoresis include, for instance, a sphere moving parallel to a plane [7][8][9][10], a sphere moving normal to a planar surface [7,[9][10][11][12][13][14], a sphere moving along the axis of a cylindrical pore [7,9,10,15], and a sphere moving at the center [16][17][18][19] or at arbitrary position [20] in a spherical cavity. There are also some examples of different particle shapes like a cylinder moving in a cylindrical pore [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

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Electrophoresis of a toroid along the axis of a cylindrical pore

Hsu

Kuo

2006

Electrophoresis

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The electrophoresis of a toroid (doughnut-shaped entity) along the axis of a long cylindrical pore is analyzed under the conditions of low surface potential and weak applied electric field. The system under consideration is capable of modeling the electrophoretic behavior of various types of biocolloid such as bacterial DNA, plasmid DNA, and anabaenopsis, in a confined space. The influences of the key parameters of the problem, including the sizes of a toroid, the radius of a pore, and the thickness of the double layer, on the electrophoretic mobility of a toroid are discussed. We show that the electrophoretic behavior of a toroid under typical conditions can be different from that of an integrated entity. For instance, although the presence of the pore wall has the effect of retarding the movement of a particle, it becomes advantageous if a toroid is sufficiently close to the boundary. Several interesting behaviors are also observed, for example, the mobility of a toroid when the boundary effect is significant can be larger than that when it is insignificant.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Electrophoresis of a toroid along the axis of a cylindrical pore

Hsu

Kuo

2006

Electrophoresis

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“…Of course, experiments always involve finite geometries, and in some cases walls play a crucial role in electrophoresis. The linear electrophoretic motion of symmetric (spherical or cylindrical) particles near insulating or dielectric walls [5][6][7][8][9][10] and in bounded cavities or channels [11][12][13][14][15][16][17][18][19][20] has been analyzed extensively. Depending on the geometry and the double-layer thickness, walls can either reduce or enhance the translational velocity, and the rotational velocity can be opposite to the rolling typical of sedimention near a wall.…”

Section: Introductionmentioning

confidence: 99%

Induced‐charge electrophoresis near a wall

Kilic

Bazant

2011

Electrophoresis

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Induced-charge electrophoresis (ICEP) has mostly been analyzed for asymmetric particles in an infinite fluid, but channel walls in real systems further break symmetry and lead to dielectrophoresis (DEP) in local field gradients. Zhao and Bau (Langmuir, 23, 4053, 2007) predicted that a metal (ideally polarizable) cylinder is repelled from an insulating wall in a DC field. We revisit this problem with an AC field and show that attraction to the wall sets in at high frequency and leads to an equilibrium distance, where DEP balances ICEP, although, in three dimensions, a metal sphere is repelled from the wall at all frequencies. This conclusion, however, does not apply to asymmetric particles. Consistent with the experiments of Gangwal et al. (Phys. Rev. Lett., 100, 058302, 2008), we show that a metal/insulator Janus particle is always attracted to the wall in an AC field. The Janus particle tends to move toward its insulating end, perpendicular to the field, but ICEP torque rotates this end toward the wall. Under some conditions, the theory predicts steady translation along the wall, perpendicular to the field, at an equilibrium tilt angle around 45 degrees, consistent with the experiments, although improved models are needed for a complete understanding of this phenomenon.

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“…Recent theoretical work for electrophoresis of a sphere in a cylinder takes into account that the pore wall also enhances the electric field compared to free solution, which partially offsets the retarding effect due to the increased drag [34,35]. The friction effect dominates though, and these more complete treatments have yet to address the high degrees of confinement (up to l = 0.8) that occurs in the present system.…”

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confidence: 89%

Comparison of oligonucleotide migration in a bicontinuous cubic phase of monoolein and water and in a fibrous agarose hydrogel

et al. 2006

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Porous hydrogels such as agarose are commonly used to analyze DNA and water-soluble proteins by electrophoresis. More recently lyotropic liquid crystals, such as the diamond cubic phase formed by the lipid monoolein and water, has become a new type of well-defined porous structure of interest for both hydrophilic and amphiphilic analytes. Here we compare these two types of matrixes by investigating the nature of retardation they confer to an oligonucleotide that migrates in their respective aqueous phases. The retardation for a 25-mer oligonucleotide was found to be about 35-fold stronger in the cubic phase than in an agarose hydrogel modified to have the same average pore size. According to modelling, the strong retardation is primarily due to the fact that hydrodynamic interaction with the continuous monoolein membrane is a stronger source of friction than the steric interactions (collisions) with discrete gel fibres. A secondary effect is that the regular liquid crystal has a narrower pore-size distribution than the random network of the agarose gel. In agreement with experiments, these two effects together predict that the retardation in the cubic phase is a 30-fold stronger than in an agarose gel with the same average pore radius.

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Electrophoretic Motion of a Spherical Particle with a Thick Double Layer in Bounded Flows

Cited by 100 publications

References 24 publications

Electrophoresis of a toroid along the axis of a cylindrical pore

Electrophoresis of a toroid along the axis of a cylindrical pore

Induced‐charge electrophoresis near a wall

Comparison of oligonucleotide migration in a bicontinuous cubic phase of monoolein and water and in a fibrous agarose hydrogel

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